The present invention relates to a grass cutting machine such as a mower or a hedge trimmer, particularly to a cutting section for a mower or a hedge trimmer.
A conventional grass cutting machine such as a mower or a hedge trimmer is usually provided with a cutting section as illustrated in FIG. 18. It is seen from FIG. 18 that such a cutting section includes a pair of elongate guide plates a and b which are arranged at upper and lower positions respectively and each secured on a transmission case c of a mower or a hedge trimmer, using two pairs of bolt/nut means d. The guide plates a and b are coupled with one another by several pairs of bolt/nut means e, arranged along the length of the guide plates. A bolt of each bolt/nut means e is surroundingly engaged with a spacer ring member (not shown) to ensure a predetermined space between the guide plates a and b. A pair of elongate cutter bars f and g lying one on top of another are slidably received in the space formed between the guide plates a and b. Each of the cutter bars f and g has a plurality of elongate guide holes (not shown) to surroundings, engage with the respective spacer ring members so that the cutter bars, when being driven reciprocatingly in the longitudinal direction thereof, can be guided properly by these spacer ring members.
Further, the rear ends of both the cutter bars f and g are drivingly connected with a crank mechanism (not shown) disposed within the transmission case c. The crank mechanism in turn is rotatingly driven by an engine through a clutch device (not shown). The transmission system thus constructed is adapted to drive the cutter bars f and g in such a manner that each of them moves reciprocatingly and always in an opposite direction to the other, longitudinally of the guide plates, whereby effecting a desired grass cutting operation.
However, with the passing of time in use of such a mower, the cutting edges of many blades on both the cutter bars f and g may become blunt, and it will be difficult to go on with the grass cutting operation if the blunt cutter bars are not replaced by new or newly properly treated ones.
In order to install a pair of new or newly properly treated cutter bars, it is at first necessary to remove the used cutter bars f and g from the position between the guide plates a and b. This however proves to be troublesome since it requires the entire cutting section including the transmission case c to be dismantled.
It is understood from FIG. 18 that in order to detach the cutter bars f and g from the cutting section, at first, all the bolt/nut means e have to be removed, then the two bolt/nut means d shall be removed from the transmission ease c and the transmission case c should be dismantled. However, many kinds of inconvenience will be encountered when such dismantlement is being conducted, especially in a field where the grass cutting operation is only half-finished.
The same inconveniences are also experienced when a pair of newly treated cutter bars are to be installed in positions on the mower, since the assembling operation shall be performed in a reversed order opposite to the above dismantlement. Moreover, even after the attachment of the newly treated cutter bars f and g has been finished, another difficulty will be encountered since a precise adjustment is required to form an exactly correct space for the cutter bars between the two guide plates a and b. Such adjustment is usually performed by screwing up or down a nut at each bolt/nut means e and this however often proves to be troublesome and the adjustment result is not always satisfactory, resulting in an incorrectly assembled cutting section.